Electrically controlled reciprocating fluid motor



A rii 27, 1943. J A LLER HAL 2,317,549

ELECTRICALLY CONTROLLED RECIPROCATING FLUID MOTOR Filed July '6, 1940 9 JLkMQw MANURL m 1 I20 R s E. w u o m L m n 5 MA? 9 0R 1 JI P Patented Apr. 27, 1943 ELECTRICALLY CONTROLLED RECIPROCAT- ING FLUID MOTOR Johan A. Muller and Ira Lawyer, Mount Gilead, Ohio, assignors to The Hydraulic Development Corporation, Inc., Wilmington, DeL, a corporation of Delaware Application July 6, 1940, Serial No. 344,278

2 Claims. (Cl. 137-139) This invention relates to hydraulic motors and, in particular, to reciprocating motors.

One object of this invention is to provide a lrvdraulic motor having a reciprocating plunger which moves at the same rate and distance as a control member, but delivering a much greater force than is applied to the control member.

Another object is to provide a hydraulic motor having a reciprocating plunger with a piston valve member cooperating with ports in the head of the plunger so as to provide a point-for-point travel of the plunger with the piston valve member. but with the output of a relatively great force for a given force applied to the piston valve member.

Another object is to provide a hydraulic motor having a reciprocating plunger with a head having a chamber therein with ports cooperating with the head of a piston valve member in such a. manner as to uncover one of these ports to permit pressure fluid to flow through the plunger head to the opposite side thereof when the piston valve member is moved in one direction, but to uncover another port permitting the discharge of pressure fluid from one side of the plunger head when the piston valve member is moved in the opposite direction, thereby providing a' follow-up motion of the plunger in correspondence with the motion of the piston valve member.

Stillanother object of the invention consists in the provision of a hydraulic motor of the type set forth above, in which the reciprocating plunger may selectively be operated semi-automatically or full automatically.

A further object of the invention is to provide a hydraulic motor having a reciprocating plunger with a piston valve member operating with ports in the head of the plunger, in which the stroke of the reciprocating plunger is variable.

It is a still further object of the invention to provide a hydraulic motor having a reciprocating plunger with a piston valve member cooperating with ports in the head of the plunger, in which the piston valve member is operable electrically.

These and other objects and advantages of the invention will appear more clearly from the following speciflcation in connection with the accompanying drawing, in which:

Figure l is a diagrammatic illustration of the entire assembly of a device according to the invention, while Figure 2 illustrates a detail thereof.

/ General arrangement In general, the hydraulic motor of this invention consists of a cylinder with a double-acting plunger therein. The plunger has a head with passages from opposite sides communicating with ports in a chamber within the head, these ports cooperating with the head of a piston valve member in such a manner as to selectively open and close oneor the other of the ports. when one port is uncovered by the piston valie head, pressure fluid is enabled to engage both sides of the plunger head and urge the latter in one direction as a result of the differential piston area provided by the rod portion of the plunger. When this port is covered and the other port uncovered, however, fluid is permitted to act against but one side of the plunger head, thereby urging the plunger in the opposite direction. The device gives a follow-up motion by reason of the fact-that when the piston valve head is moved a given distance in one direction, the unby the motion of the plunger is vastly greater than the force necessary to move the piston valve head in one direction or the other. In other words, a point-for-point correspondence is effected between the motion of the piston valve member and the resulting motion of the plunger.

The piston valve member cooperating with the ports in the plunger head is operable by an electric motor having a hollow shaft connected with the rotor and provided on the inside thereof with a thread which engages a correspondingly threaded portion on the piston valve'member. In this way, rotation of the motor rotor will cause movement of the piston valve member in one or the other direction in correspondence with the rotation of said rotor. The piston valve member, furthermore, cooperates with switches controlling the energization circuit of the motor so as to interrupt the said energization circuit after the piston valve member has traveled a predetermined distance.

According to a further feature of the invention, the energization circuit of the motor has associated therewith a controlling circuit to anable'selectively manual, semi-automatic and f automatic operation of the device.

This invention is capable of use as a servomotor or as an auxiliary motor for controlling annular partition I3, having a bore with a bushat the pressure inlet port 3 I the servomotors of large hydraulic pumps. It may be used, however, in any position where it is desired to obtain a greatly increased force with a corresponding rate and distance of motion, such as in controlling the positions of members in heavy machinery, such as steel mill machinery. Another application is for regulating the position of the blade of a road grader so as to regulate the cutting depth. The invention may further be used in connection with a smaller press for forcing bushings, for riveting, or for assembling. The device may also be used as a hydraulic jack or hoist.

Structural arrangement Referring to the drawing in, detail, Figure 1 shows a preferred embodiment of the hydraulic motor of this invention as consisting of a casing I9 with bores H and I2 therein, separated by an ing I 5 therein( The bushing I5, which may be a bronze bushing, fits closely around the motor plunger I6 so as to prevent excessive leakage. The motor plunger I6 is provided with a head I! having L-shaped passageways I8 and I9 communicating with ports 29 and 2I in a sleeve 22 mounted within a longitudinal bore 23 within the plunger head IT. The bore 23 continues in the counterbore 24 to provide an annular wall 25 against which the sleeve 22 abuts.

Beyond the-counter bore 29 is a longitudinal bore or passageway 26 extending through the plunger I6 to the cross passageways 27 opening out into the bore I2. Beyond the cross passageways 21 the motor plunger I6, passes through an annular end wall 28, having beyond it a. packing 29, compressed by a gland 39, for preventing leakage from the device. Threaded ports 3| and 32 open;respectively, into the bores II and I2. The port 3I is connected by means of a conduit 33 with one side of a variable delivery pump 34, while the other side of the variable delivery pump 34 communicates on one hand with a conduit 35 leading to the port 32, and on the other hand with a fluid reservoir or tank 48. A conduit 36 branching off from the conduit 33 comprises a pressure relief valve 3! and leads to the conduit 35. The of the pressure relief valve 3'8 consists in relieving excessive pressure in the conduit 33.

The inner surfaceof the sleeve 22 forms a bore 38 for receiving a piston valve head 39 upon a piston valve rod 49, having a reduced diameter portion 4I connected with the piston valve head 39. Secured to the end of the sleeve 22, as by screws 42, is a retaining ring 43, for preventing the piston valve head 39 from being withdrawn from the bore 39, in the event that the valve rod 49 is moved when no pressure fluid is being supplied The bore II serves as a pressure chamber and is provided with a cylindrical head 94 secured to the casing I9, by any convenient means, for instance by screws 45, and containing a packing 46 compressed by a gland 41, for prever leakage around the valve rod 99. Also moon upon the cylinder head 44, by means of st is an electric motor, generally designates 5 The motor 49 has a hollow shaft 59 with an a, thread 5I engaging a correspondingly threaded portion 52 on the piston valve rod 49. The hollow shaft 59 carries the rotor 53. The entire assembly runs in ball bearings 54. The stator is indicated by the reference numeral 55.

Attached to the end of the motor, for instance 7 the key 58 is provided but on the opposite side thereof, is a groove 69 which either acts itself as a cam or has inserted therein cam members 6| (see Figure 2) to actuate limit switches 62 and 63 through plungers 69 and 65 which are held against the groove 69 or cams 6! by springs 66, 61.

The motor 49 may be controlled by an electric circuit, as shown. The double throw switch 68 is adapted to start, stop and reverse the motor through contactors, generally designated 69 and. 79. The contactor 69 comprises an armature II with blades I2, I3, 74 and 15. The-blades I3, I4 and I5 are adapted, respectively, to bridge the terminals I6, TI, I6, I9, 89 and 8|. The terminals I6, I8 and 89 are respectively connected with the motor through lines 82, 83 and 84. The lines 82, 83 and 84 are respectively connected through lines 85,86 and 81 with the terminals 88, 89 and 99, pertaining to the contactor I9.

Cooperating with the terminals 88, 89, 99, are terminals 9|, 92, 93 respectively connected with the terminals SI, 19 and 11. The armature 94 of the contactor 19 comprises blades 95, 96, 91, 98, adapted to bridge the temiinals 88, 9|, 89, 92, 99, 93, 99 and I99. The blade 12 of the contactor 69 is adapted to bridge the terminals I9I and I92, the latter of which is connected by a line I93 with a line I94 and the terminal I99. The line line I96 with a switch lever I91 which, in its closed position, connects the line I96 with the line I99 leading to the terminal I99. The terminal I 99 pertains to the double throw switch 68 and is adapted to be contacted with a switch lever II9 of the double throw switch 68. The switch lever H9 is urged, by means of a spring III, into an intermediate position in which it neither contacts the terminal I99 nor the terminal II2, likewise pertaining to the switch 68. Branching ofi from the line I98 is the energizing coil H3 of the solenoid, generally designated II4, associated with the armature II. The terminal H2 is connected by means of a line I I5 with a terminal H6 adapted to be connected by means of a switch lever III with a line II8 leading to the terminal 99.

The switch lever I I9 of the double throw switch 68 is connected by line II9 with a contact I29, adapted to be contacted by the switch arm I2! which, in its turn, is connected by line I94 with the main supply line I22. A second main supply line I23 is connected by means of a line I24 with a line I25, interconnecting the terminals 19 and 92. A third main supply line I26 is connected by means of the lines I21 and I28 with the terminals 8i and 9|.

The switch arm I2l is also adapted to contact a terminal I29 connected by means of the line I39 with a toggle lever switch arm I-3I, which is adapted, by means of itsarm I32, selectively to contact the terminal I33 connected by line I34 with the line I98, or the terminal I35 connected by line I36 with the line II 5. Branching oif from the line H5 is the energizing coil I37 of the contactor 19'. The toggle lever I3I is adapted to be operated in one direction by an The cam 6| has a split member with a slot I40 which may be spread apart by screwing screw I4la into the threaded portion I after the cam 6I has been inserted at a desired place in the groove 60 of the piston valve rod 40. 2

Operation the conduit 33 and the port 3I into the bore II,

from where it passes downwardly through the L-shaped passageway I8 into the port 20. Now the switch lever IIO is shifted toward its lefthand position so asto contact the terminal I03. Current will then flow from the main supply line I22, through line I04, the switch arm I2I, the line II3, the switch lever IIO, the line I03, the coil II3, the line I42, the blade I43 of the limit switch 63 and through the line I44 to the main supply line I26. Due to the energization of the coil II3 the armature H is attracted, thereby having its blades 12, 13, 14 and 15 close the adjacent terminals. The blade 12 engaging the terminals IM and I02 closes the holding circuit which comprises the main supply line I22, the line I04, line I03, terminal I02, blade 12, terminal IOI, line I06, lever arm I01, line I03, coil II3, line I42, blade I43 and lines I44 and I26. Furthermore, the blades 13, 14 and 15, in cooperation with adjacent terminals, close the energizing circuit for the motor 43 so that, due to the rotation of the rotor 53, the engagement of the motor shaft 50 with the threaded portion 52 causes an upward movement of the valve rod 40 with its piston head 33. As a result of this upward movement of the piston valve head 33, fluid will flow from the L-shaped passageway I3 through the bore 33 of the sleeve 22 into the space beneath the plunger head I1. The plunger head I1 is provided with upper and lower head areas I45 and I46, respectively, the difference between these areas providing a differential piston area which is elfective when both of the head areas I45 and I46 are supplied simultaneously with pressure fluid. This occurs when the upper movement of the valve rod 40 and valve head 33 uncovers the sleeve port so that pressure fluid acts simultaneously on the small annular area I45 and the large annular area I46. The effective piston head area thus brought into play is equal to the diiference in the areas of the portions I45 and I46, with the balance in favor of the lower head area I46. As a consequence, the plunger I6 and plunger head I1 are moved upwardly. When this occurs, however, the port 20 likewise is moved upwardly and will tend to pass the lower edge of the valve head 33 to again cover up the port 20. Similarly, the port 2I will tend to cut of! communication between the head passageway I3 and the longitudinal bore 26 in the plunger I6. However, since the motor 43 is still running, thepiston valve head'33 will continuously move upwardly.

The plunger head [1 therefore, out a follow-up movement until the plunger head I1 has reached its uppermost position or, if a shorter stroke is desired, until the limit switch 33 is actuated either by the cam surface of the groove 60 or the cam member 6| in the said groove. Actuation of the limit switch 63 causes interruption of the holding circuit for the solenoid II4 so that the energizing circuit for the motor 43 will be interrupted and the motor will come to a standstill.

If it is now desired to retract the motor plunger the spring III, is now shifted to contactthe ter minal I I2. Current will then flow from the main supply line I22 to the line I04, the switch lever arm I2I, the line II3, the lever II3, the line 6, the coil I31 and the line I41, through the limit switch 62, from where it will flow through the line I44 to the main supply line I23. This circuit will energize the coil I31, thereby causing attraction of the armature 34. The switch blade 33 will then contact the terminals 33 and I00, thereby establishing a holding circuit comprising the main supply line I22, the line I04, terminal I33,

switch blade 33, terminal 33, lever arm II1, line II5, coil- I31, line I41, limit switch 62 and line I44 and the main supply line I26. The switch blades 35, 36 and 31 will then close the energizing circuit for the motor 43 so that the latter rotates in a direction opposite to its previous direction of rotation. As a result thereof, the threaded portion 52 of the valve rod and, thereby, also the valve head 33 will be moved downwardly. This opens up the L-shaped head passageway I3 for communication through the port 2| with the longitudinal passageway 23 and, at the same time, closes oif the port 20 of the L-shaped head passageway I3 against the discharge of pressure fluid theret-hrough. Consequently, the pressure fluid from the pump 34 is applied only within the upper end of the bore II against the annular plunger head area I45, while all pressure is released against the lower plunger head area I46. The plunger I6, therefore, moves downwardly and the fluid displaced from beneath the plunger I6 is moving upwardly through the passageway I3, the port 2I, the counterbore 24, the plunger passageway 26, the cross passa eway 21, th cylinder bore I2, the outlet port 32 and the conduit 36, a part to the suction side of the pump 34 and a part to the fluid tank 43. Since the motor 43 continues running, there'will be a follow-up movement of the plunger head I1, similar to the follow-up movement described above in connection with the upward movement of the plunger l6. The plunger head I1 will come to a standstill either when it engages the head 44 or, if an earlier stop is desired, when the limit switch 62 is actuated by the cam surface of the groove 60 or the cam member 6I therein, thereby interrupting the energizing circuit for the motor 43.

It should be noted that the movement of the valve rod 40 may be stopped at any desired point and time by mere operation of the lever arm I31 or II1, respectively, to break the energizing circult for the coil H3 and I31, respectively.

So far, manual operation has been described. If semi-automatic operation is desired, in other words, if the plunger I3 is to carry out an upward anda downward stroke and is then automatically to stop, the lever arm I2I is to be shifted so as to disengage the terminal I23 and engage the terminal I23. Furthermore, the cam toggle lever arm i3l.

member 8| in the groove 50 is so adiusted that it will not'engage the limit switch 63 at the end of the upward stroke of the plunger It. On the other hand, the arm M8 isso adjusted that, at the desired end of the upward stroke of the plunger IE, it will engage and shift the toggle lever switch arm it, so that the'to'ggle lever switch arm I32 disengages the terminal I33 and engages the terminal! 35. The operation of the device, in this instance, will be the same as described above with the exception that the limit switch 53 will not be operated but instead theredesired time, be interrupted by operation of the lever arm Ill] or ill.

of the direction of rotation of the motor 69 will be changed at the end of the upward stroke of the plunger l5 by the shifting movement of the At the end of its desired downward stroke, the plunger IE will come to a standstill, in the manner described above.

If full automatic operation is desired, it will be necessary, in addition to the adjustment to be efiected for semi-automatic operation, also to make the limit switch 62 inoperative by correspondingly adjusting the cam member 6i pertaining thereto. Furthermore, the arm M9 will be adjusted on the rod I50 so that, at the end of the downward stroke of the plunger i6, the arm I49 switches thetoggle lever arm I3! in a direction opposite to the direction in which the lever arm IN is shifted by the arm M8. It will be obvious that, after efiecting of the said adjustment,

' the plunger lSwill continuously carry out a desired number of cycles. The stroke of the plunger i6. may, in this instance, be controlled by the It will be understood that we desire to comprehend within our invention such modifications as come within the scope of th claims and the invention.

Having thus fully described our invention,

.what we claim as new and desire to secure by Letters Patent, is:

1. In combination in a servomotor, a valve, a reversible electric motor, a reciprocable control rod arranged in alignment with the motor shaft of said electric motor for-operating said valve, means for positively preventing rotation of said control rod in all positions of its movement, screw parting longitudinal movement thereon to opposition of the arms 8 and 149. As previously stated, the operation of the device may, at any crate said valve, and adjustable cam means supported by said control rod and adapted in response to the travel of said control rod selectively to open and close said circuit for controlling said motor.

JOHAN A. MUILER. RA B. LAWYER. 

